How to fix between date to date error in php - php

Question

When I try to Search Between two dates all are working display on reports-details.php but When I try to fresh reload on reports-details.php show this error Warning:
Invalid argument supplied for foreach() in C:\xampp\htdocs\parking
reservation\admin\reports-details.php on line 52
reports.php content is:
<form action="reports-details.php" method="POST">
<label>From Date</label>
<input type="date" name="start_date">
<label>To Date</label>
<input type="date" name="end_date">
<button name="search">Search</button>
</form>
back-end-reports.php
<?php
include 'config.php';
class report extends Connection{
public function managereport(){
if (isset($_POST['search'])) {
$start_date = $_POST['start_date'];
$end_date = $_POST['end_date'];
$sqlselect = "SELECT * FROM tbl_customers WHERE test_date BETWEEN '$start_date' AND '$end_date' ORDER BY test_date";
$result = $this->conn()->query($sqlselect);
$result->execute();
return $result->fetchAll();
}
}
}
$new_vehicle = new report();
$new_vehicle->managereport();
?>
reports-details.php
<?php
include '../back-end/back-end-reports.php';
$result = new report();
$query = $result->managereport();
?>
<?php $id = 1; foreach($query as $row) { ?>
<tbody>
<tr>
<td><?php echo $id; ?></td>
<td><?php echo $row['serial']; ?></td>
<td><?php echo $row['fullname']; ?></td>
<td><?php echo $row['num_plate']; ?></td>
<td>View | <a class="text-dark" href="print.php">Print</a></td>
</tr>
</tbody>
<?php $id++; } ?>

Answer 1

Your issue here is the if statement in your function
if (isset($_POST['search'])) {
When you refresh your page there is no post data so the managereport returns nothing. The value of $query is therefore empty and so you cant iterate over it in the foreach loop.
My suggestion would be that your mangerreport() should return an empty array in the situation where there is no post data i.e
public function managereport(){
if (isset($_POST['search'])) {
$start_date = $_POST['start_date'];
$end_date = $_POST['end_date'];
$sqlselect = "SELECT * FROM tbl_customers WHERE test_date BETWEEN '$start_date' AND '$end_date' ORDER BY test_date";
$result = $this->conn()->query($sqlselect);
$result->execute();
return $result->fetchAll();
} else {
return array();
}
}

Answer 2

<?php $id = 1; foreach($query as $row) { ?>
When using the foreach loop, you must first judge the array $query, otherwise you will be prompted to report an error like this Invalid argument supplied for foreach() , you can add judgment before the loop,
<?php $id = 1; if (is_array($query) && count($query)) {
foreach($query as $row) { ?>
<tbody>
<tr>
<td><?php echo $id; ?></td>
<td><?php echo $row['serial']; ?></td>
<td><?php echo $row['fullname']; ?></td>
<td><?php echo $row['num_plate']; ?></td>
<td>View | <a class="text-dark" href="print.php">Print</a></td>
</tr>
</tbody>
<?php $id++; } } ?>